![]() YCbCr and Y′CbCr are a practical approximation to color processing and perceptual uniformity, where the primary colors corresponding roughly to red, green and blue are processed into perceptually meaningful information. Same happens with JPEG: it has BT.601 matrix derived from System M primaries, yet the primaries of most images are BT.709.Ĭathode ray tube displays are driven by red, green, and blue voltage signals, but these RGB signals are not efficient as a representation for storage and transmission, since they have a lot of redundancy. Nevertheless that rule does not apply to P3-D65 primaries used by Netflix with BT.2020-NCL matrix, so that means matrix was not derived from primaries, but now Netflix allows BT.2020 primaries (since 2021). The transformation is defined in equations 32, 33 in ITU-T H.273. If the underlying RGB color space is absolute, the Y′CbCr color space is an absolute color space as well conversely, if the RGB space is ill-defined, so is Y′CbCr. Y′CbCr color spaces are defined by a mathematical coordinate transformation from an associated RGB primaries and white point. Y′ (with prime) is distinguished from Y, which is luminance, meaning that light intensity is nonlinearly encoded based on gamma corrected RGB primaries. Y′ is the luma component and C B and C R are the blue-difference and red-difference chroma components. YCbCr, Y′CbCr, or Y Pb/Cb Pr/Cr, also written as YC BC R or Y′C BC R, is a family of color spaces used as a part of the color image pipeline in video and digital photography systems. ![]() The Y′ image is essentially a greyscale copy of the main image. A visualization of YCbCr color space The CbCr plane at constant luma Y′=0.5 A color image and its Y′, C B and C R components.
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